The cover lid of the yarn brake for shuttleless weaving machines as known from EP 02 94 323 A (U.S. Pat. No. 4,875,506) can be lifted in parallel fashion from the fixed braking surface over a small stroke only and by means of two links. The links pivot against spring force about adjusting arbors which extend perpendicular to the yarn path. Since the cover lid partly covers the braking zone even in the lifted position, it is not possible to then gain free access or to have an unobstructed view into the braking zone. Alternatively, the braking lamella may be secured to an arbor which is fixed in the housing against rotation. The braking lamella is biased against the fixed braking surface. The braking zone cannot be cleared completely when the lamella is lifted by hand.
The cover lid of the yarn brake according to EP 04 98 758 A (U.S. Pat. No. 5,244,164) is movable over a short stroke about an adjusting arbor which extends parallel to the fixed braking surface. Since the braking zone cannot be cleared totally, neither unobstructed access nor a free view into the braking zone are possible. The yarn brake is equipped with a pressurised air-cleaning system which is provided at the cover lid or at the brake housing, respectively. The cleaning system directs air jets into the braking zone crosswise to the yarn running direction.
The braking lamella of the yarn brake for a rapier weaving machine as known from U.S. Pat. No. 6,161,595 is permanently pressed by a coil spring with a basic load against the fixed braking surface. The coil spring is supported by a portal-shaped structure. In addition, the contact pressure of the braking lamella is controlled by magnet force depending on the weaving cycles. Yarn brakes produced according to U.S. Pat. No. 6,161,595 and as employed in practice comprise channels for pressurised air. The channels are integrated into the housing and lead to channel ports. The air nozzles open freely at the side of the braking nip defined between the braking lamella and the fixed braking surface. This design negatively influences the efficiency of cleaning processes and causes high consumption of pressurised air.
For maintenance, for cleaning, and if necessary, for checking the degree of contamination, for replacing the braking lamella, or for re-threading and for similar operations free access and an unobstructed view to or into the braking zone would be expedient. This ought to be possible rapidly and without significant readjustments or mounting work steps. Furthermore, the yarn brake ought to be cleaned efficiently by pressurised air in order to remove lint collected in the area of the braking zone. These requirements occurring in practice cannot be met satisfactorily by the known yarn brakes.